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Discussion Starter · #1 ·
So I was reading on this forum that if I get front adjustables my steering issues will be fixed. Right now I have a 4 inch lift with rear adjustable uppers and SYE kit. I'm having slight steering issues like when I'm driving I'm pulling either left or right. Does this mean my caster is off and will installing the adjustables correct it? Thanks guys!

And some pics for fun that I took yesterday



 

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I had a similar issue. God really bad when hitting pot holes and at higher speeds. Got the rubicon express adjustable lower control arms. Cost me about 500 bucks and the issue is about 90% fixed. But I have a 5.5" lift and from what I have read that little bit is normal for mine. Goodluck
 

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It depends, I did not have pulling issues, but I just put adjustable arms all the way around (Curie) It definately handles better, but it now makes an obnoxious growl when turning sharp and the Jeep rolls towards the turn. The growl is worth it for the handling improvement.
 

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I believe it is where the axle is angled in such a way that the wheels can never be perfectly aligned?
Once you've learned what caster is, you'll have a better understanding on why exactly adjustable-length control arms can help you. Until then you'll just be shooting in the dark.

In this particular case, Google is your friend.
 

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Discussion Starter · #8 ·
Okay so from what I understand is from the factory, everything is set up perfectly, obviously. When I lifted it with the stock control arms, it pulled the axle towards the middle of the Jeep while rolling my axle forward a little bit. This offsets the caster because the axle is no longer in the factory position. By adding adjustable control arms I can more or less return it to the factory settings by lengthening the lowers. Am I getting it?
 

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Discussion Starter · #9 ·
Of course everything depends on tire size also. I'm running 33s on a four inch lift. Is 5-6 degrees okay for me?
 

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Okay so from what I understand is from the factory, everything is set up perfectly, obviously. When I lifted it with the stock control arms, it pulled the axle towards the middle of the Jeep while rolling my axle forward a little bit. This offsets the caster because the axle is no longer in the factory position. By adding adjustable control arms I can more or less return it to the factory settings by lengthening the lowers. Am I getting it?
You've got it almost all right. Except when you you a lift in, caster actually decreases, meaning the angle between the pinion and flat ground is decreased. So that means the axle would have to rotate rearward. You will still benefit from new arms because they'll allow for more misalignment (suspension travel) and to push the axle forward a tad so it sits correctly at full bump.
 

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From my understanding caster is actually usually decreased. It is changed in 2 basic ways. The small one is because the axle is swinging in an arc on arms that point to an imaginary spot. When it rotates the caster actually decreases from that. Now if the arms were the same length this would be the only factor. However the big way caster is affect by a lift is because of the lengths of the control arms. The uppers are a good bit shorter than the lowers and as they travel through their respective arcs the shorter arm has a shorter arc radius compared to the lower arms. Because they are fixed points on the axle (and different points on the frame), it twists the axle decreasing caster. That's the simple version. This all actually changes the position of the axle as well forward and backward but not really enough to make a difference (and only at ride height, position stays the same at full bump etc). I hope that makes sense ( and is correct, going from memory here). Been a while since I've had to do math! haha. Remember you have to balance castor for handling with a proper pinion angle. I don't think you'll have issues at your height but just keep that in mind.


Not to call you out pstov but positive caster is from front bottom to rear top. So by your line of thinking rotating the axle back would decrease the caster. He would most likely want to increase it depending on tire/lift size.

Because we have positive caster, when it is decrease the axle actually rolls forward not rearward. Picture the arms in straight lines over each other and how the axle would be rotated if that were possible. Now swing down and back in the direction it travels after being lifted. The axle rotates forward.
measure caster at the ball joints against a vertical line through the axle. And the axle is actually still fine at full bump until you start changing arm lengths.

I may have just not understood your post exactly when you said it would have to rotate rearward so if it's a miscommunication I'm sorry.
 

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Not you're fault. My wording was shoddy at best. Should've taken more time on that one. But I was trying to say the same thing, you just did it a little better. Thanks for clearing it up!
 

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No problem. I had to think on it a little bit while writing it up too. It's really not that simple once you take arc lengths and both fixed end points and the fact that they don't mount the links the same place or height or length and I don't have any definite numbers on hand... But that's the fun of geometry right. :rofl:

It's too late for this kind of thinking anyways.
 

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No problem. I had to think on it a little bit while writing it up too. It's really not that simple once you take arc lengths and both fixed end points and the fact that they don't mount the links the same place or height or length and I don't have any definite numbers on hand... But that's the fun of geometry right. :rofl:

It's too late for this kind of thinking anyways.
I agree! Ha I've been studying for the MCAT lately so all this Jeep knowledge is getting crammed in a corner until I can dump all this crap out on the 15th.
 

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Caster



Pinion angle and caster angle are inversely related on solid axles and unless you cut the inner C's off and rotate them, that relationship is fixed.

There are other things to consider when rotating the axle housing and moving it fore-aft with adjustable control arms. A total understanding of the dynamics involved is really needed before you start messing with it. It's not complicated or difficult to understand but some people tend to have issues with it.
 

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Reissigree: I think if you get some Pro Comp arms your troubles will all go away. Imped also highly endorses Pro comp arms and any fixed control arm with high quality poly bushings. Your ride will transform. :D :angel:
 

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Discussion Starter · #19 ·
Reissigree: I think if you get some Pro Comp arms your troubles will all go away. Imped also highly endorses Pro comp arms and any fixed control arm with high quality poly bushings. Your ride will transform. :D :angel:
Hahaha I think I may go with Currie :hide:
 
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